If two trains each having length of 300 m are running in opposite direction to each other having speed of 60 km/hr and 102 km/hr respectively. Calculate the time in which they cross each other completely.

Given:

Length of Train 1 (L₁) = 300 m

Length of Train 2 (L₂) = 300 m

Speed of Train 1 (S₁) = 60 km/hr

Speed of Train 2 (S₂) = 102 km/hr

Formula used:

Relative Speed (S_rel) = S₁ + S₂ (as trains are moving in opposite directions)

Time (t) = Total Length / Relative Speed

Calculation:

Relative Speed:

S_rel = 60 + 102 = 162 km/hr

Convert speed to m/s:

S_rel = 162 × (1000 / 3600)

⇒ S_rel = 45 m/s

Total Length:

Total Length = L₁ + L₂

⇒ Total Length = 300 + 300 = 600 m

Time:

t = Total Length / Relative Speed

⇒ t = 600 / 45

⇒ t = 13.33 seconds

∴ The correct answer is option (1).